There are many examples of the introduction of electronic blackboard systems, such as for the purposes of adopting IT (Information Technology) in the classroom or raising efficiency in business conferences.
Patent Document 1 discloses a projector system that can be used as an electronic blackboard system.
The projector system described in Patent Document 1 includes a projector, an electronic stylus, and a stylus manipulation detection means. The electronic stylus is used to indicate a portion of an image (hereinbelow referred to as a “displayed image”) that the projector has displayed on a projection surface such as a wall and to add characters or pictures to a portion of the displayed image. The electronic stylus supplies a signal such as an infrared ray that accords with jotting manipulation. The stylus-tip manipulation detection means detects the signal that is supplied from the electronic stylus with respect to a portion of the displayed image that was indicated by the electronic stylus. The projector adds characters or pictures that accord with the detection result of the pen-tip manipulation detection means to the portion of the displayed image that was indicated by the electronic stylus.